Oh oh oh! let me answer...pleaseeeee!
lol
In my honest opinion liking/not liking this game depends on what game you want this to be opposed to what it actually is.
First off ... whilst the game has a single player side to it (even more since the recent DLC) it is, at its core, cooperative multiplayer. Picking up players to play alongside however is RIDICULOUSLY EASY though... of course this may be a problem if you have social anxiety issues but the whole game, including the singleplayer "story" can be played cooperatively.
Yup, from start to finish you can ... and perhaps will enjoy it more ...if you play with friends.
This game is NOT a Call of Duty, it is NOT a first person shooter. This game is really an MMORPG .... if you have experience with those style games you will notice lots of similarities such as Instances/Dungeons etc. Like these games there are health bars, bosses are damage sponges as well as having specific weaknesses you have to learn....there are even "spells"! (obviously in this game advanced technology, but some are pretty difficult to write off with that explanation still)
If you want a game to run-n-gun .... THIS IS NOT THE GAME FOR YOU. Whilst lots of time will be gunning down enemies in a similar cover based, third person method to Gears of War there is a very deep skill based set where you must balance primary character skills, attributes, armour, weapons, modifications etc. If you don't pay attention to this you won't do anywhere as well...and it is DEEP. For example I now often spend more time crafting, re-rolling, managing inventory and moving items about on my character to get the stats I want than shooting things.
In the early part of the game (I'd say about 5 hours at least of gameplay), which you can solo, all this won't matter much and you can bash through on sheer force of weapons. Once you hit level cap though and start moving to PvP and higher missions etc you need to look closer.
The PvP is utterly open!! There are no sides to take, no morals to address....take the good and bad on that if you venture into the PvP area and be warned.
PvE is always being added too, we've had two FREE DLC packs already, paid ones to come still....all have extend the life of the PvE game nicely.
This game is best enjoyed at a medium pace, enjoy and roam the highly detailed streets....laugh or be shocked at the conversations you hear or CCTV you watch (seriously, some are upsetting!)...and remember that some big chunks of later game can really only be done as a team and that the whole game is best enjoyed as a group.